Amine-boron adducts as reduced odor catalyst compositions for the production of polyurethanes

ABSTRACT

An amine-boron composition for catalyzing the urethane reaction, particularly in preparing a polyurethane foam, consisting essentially of the addition product of a tertiary amine and a boron compound of the formula R n  B(OH) 3-n  where 
     n=0 or 1, and 
     R=C 1  -C 8  alkyl, C 5  -C 8  cycloalkyl or C 6  -C 10  aryl. 
     Preferred catalysts are prepared by mixing triethylenediamine with boric acid.

FIELD OF THE INVENTION

The present invention relates to the use of tertiary amines as catalystsfor producing polyurethanes.

BACKGROUND OF THE INVENTION

The commercial production of polyurethanes via isocyanate poly additionreactions requires the use of catalysts. Tertiary amines were widelyaccepted in the industry as versatile polyurethane catalysts. They aregenerally stable in the presence of standard polyurethane formulationcomponents and can impact both the blowing (water-isocyanate) andgelling (polyol-isocyanate) reactions. Unfortunately, a number ofcommonly used tertiary amine catalysts are relatively volatile and havean unpleasant smell. Even at low use levels, they may impart anoticeably pungent odor to the polyurethane formulation. It would bedesirable to identify alternatives to standard tertiary amine catalystswhich are not malodorous, yet exhibit the same type of activity inisocyanate polyaddition reactions.

One strategy for the reduction of odor associated with tertiary aminecatalysts is the identification of less volatile structures. Theliterature teaches numerous techniques for reducing volatility,particularly increasing molecular weight or improving hydrogen bondingcapability.

U.S. Pat. No. 4,026,840 describes the use of hydroxy-functionalizedtertiary amines as polyurethane catalysts, particularly useful for theproduction of polyisocyanurate. In addition to lower volatility, suchmaterials also contain reactive functionality which bind the amine intothe final product. Typically, however, catalysts which are non-fugitiveby way of reaction with isocyanate must be used at relatively highlevels to compensate for immobilization of the tertiary aminefunctionality during urethane part production.

U.S. Pat. No. 4,006,124 which is an example of lower volatility beingachieved by metal complex formation, describes the use of amidine-metalcomplexes as polyurethane catalysts.

U.S. Pat. No. 4,857,560 mentions reduced odor emission as an additionaladvantage of the disclosed expansion catalysts formed from tertiaryamines and an acid mixture of (1) boric acid and (2) a carboxylic acid.Unfortunately, strong organic acid containing catalysts tend to showmasterbatch instability and corrosivity. Furthermore, carboxylic acidfunctionality is reactive with and can consume expensive isocyanatefunctionality, resulting in the formation of amide rather than the morestandard urethane or urea segments in a resulting part.

Boric acid derivatives have not otherwise been used in combination withtertiary amines to effect amine odor reduction. Other uses of boric acidin polyurethane formulations, however, have been described.

CA 99(6):39229a notes that boric acid, when used as a filler at 10-40%,decelerates foaming in polyurethanes based on Laprol 805 and Lapramol294 polyether polyols, polyisocyanate, Freon 113 and water.

"Int. Prog. Urethanes 1980", 2, 153-73 describes the use of boric acidas a blowing agent, its behavior being almost equal to that of water.Neither reference describes the effect of boric acid at use levelstypified by a catalyst, nor do they indicate the effect of boric acid onpolyurethane catalysis in the presence of a tertiary amine.

U.S. Pat. No. 4,611,013 describes the use of quarternary ammoniumborates to effect the concurrent trimerization/carbodiimidization ofpolyisocyanates. The borates are prepared from boric acid, alcohols andquarternary ammonium hydroxides and as such are not derived fromtertiary amines. Other examples are given by U.S. Pat. Nos. 4,530,938and 4,425,444.

U.S. Pat. No. 3,193,515; U.S. Pat. No. 3,127,404 and FR 2,301,554disclose the use of boric acid in the preparation of an ammonium saltpolyurethane catalyst from triethylenediamine and a glycol borate acid.Glycol borate acids are prepared by heating mixtures containing notsubstantially less than 0.5 moles of boric acid per mole glycerol oralternative vicinal glycol to effect acid complex formation. Theadvantage of such catalyst composition is delayed activity and/oraccelerated cure. Unfortunately, the preferred catalyst compositions arehighly viscous because a low glycol/boric acid ratio is required tominimize the amount of glycol delivered into a formulation. The additionof low molecular weight glycol into polyurethane parts, particularlyfoam parts, is typically avoided to prevent unnecessary consumption ofexpensive isocyanate. Further, glycols can negatively impact physicalproperties.

"J. Org. Chem." 1972, 37 (14), 2232 discloses that monodentate nitrogennucleophiles do not react significantly with boric acid in aqueoussolution.

SUMMARY OF THE INVENTION

The present invention provides a composition for catalyzing the reactionbetween an isocyanate and a compound containing a reactive hydrogen,e.g. the urethane reaction for making polyurethane. The catalystcomposition consists essentially of a tertiary amine urethane catalystin combination with a boron compound of the formula R_(n) B(OH)_(3-n)where

n=0 or 1, and

R=C₁ -C₈ alkyl, C₅ -C₈ cycloalkyl or C₆ -C₁₀ aryl.

As an advantage of these catalyst compositions there is a significantreduction in amine odor compared to standard polyurethane catalystcompositions containing volatile tertiary amines. Improved reactivitiesand physical properties have been noted when such amine-boroncompositions are used as catalysts for isocyanate polyadditionreactions.

Other distinct advantages over boron-containing prior art catalystcompositions include reduced viscosity and lower corrosivity.

DETAILED DESCRIPTION OF THE INVENTION

The catalyst compositions according to the invention can catalyze thereaction between an isocyanate functionality and an activehydrogen-containing compound, i.e. an alcohol, an amine or water,especially the urethane (gelling) reaction to make polyurethanes and theblowing reaction of water with isocyanate to release carbon dioxide formaking foamed polyurethanes, or the trimerization of the isocyanatefunctionality to form polyisocyanurates.

The polyurethane products are prepared using suitable organicpolyisocyanates well known in the art including, for example,hexamethylene diisocyanate, phenylene diisocyanate, toluene diisocyanate("TDI") and 4,4'-diphenylmethane diisocyanate. Especially suitable arethe 2,4- and 2,6-TDIs individually or together as their commerciallyavailable mixtures. Other suitable isocyanates are mixtures ofdiisocyanates known commercially as "crude MDI", also known as PAPI,which contain about 60% of 4,4'-diphenylmethane diiso- cyanate alongwith other isomeric and analogous higher polyisocyanates. Also suitableare "prepolymers" of these polyisocyanates comprising a partiallyprereacted mixture of polyisocyanates and polyether or polyesterpolyols.

Illustrative of suitable polyols as a component of the polyurethanecomposition are the polyalkylene ether and polyester polyols. Thepolyalkylene ether polyols include the poly(alkylene oxide) polymerssuch as poly(ethylene oxide) and poly(propylene oxide) polymers andcopolymers with terminal hydroxyl groups derived from polyhydriccompounds, including diols and triols; for example, among others,ethylene glycol, propylene glycol, 1,3-butane diol, 1,4-butane diol,1,6-hexane diol, neopentyl glycol, diethylene glycol, dipropyleneglycol, pentaerythritol, glycerol, diglycerol, trimethylol propane andlike low molecular weight polyols.

In the practice of this invention, a single high molecular weightpolyether polyol may be used. Also, mixtures of high molecular weightpolyether polyols such as mixtures of di- and tri-functional materialsand/or different molecular weight or different chemical compositionmaterials may be used.

Useful polyester polyols including those produced by reacting adicarboxylic acid with an excess of a diol, for example, adipic acidwith ethylene glycol or butanediol, or reacting a lactone with an excessof a diol such as reacting caprolactone with propylene glycol.

In addition to the polyether and polyester polyols, the masterbatches,or premix compositions, frequently contain a polymer polyol. Polymerpolyols are used in polyurethane foam to increase the foam's resistanceto deformation, i.e. to increase the load-bearing properties of thefoam. Currently, two different types of polymer polyols are used toachieve load-bearing improvement. The first type, described as a graftpolyol, consists of a triol on which vinyl monomers are graftcopolymerized. Styrene and acrylonitrile are the usual monomers ofchoice. The second type, polyurea modified polyols, is a polyolcontaining a polyurea dispersion formed by the reaction of a diamine andTDI. Since TDI is used in excess, some of the TDI may react with boththe polyol and polyurea. This second type of polymer polyol has avariant called PIPA polyol which is formed by the in-situ polymerizationof TDI and alkanolamine in the polyol. Depending on the load-bearingrequirements, polymer polyols may comprise 20-80% of the polyol portionof the masterbatch.

Other typical agents found in the polyurethane foam formulations includecrosslinkers such as ethylene glycol, butanediol, diethanolamine,diisopropanolamine, triethanolamine and/or tripropanolamine; blowingagents such as water, methylene chloride, trichlorofluoromethane and thelike; and cell stabilizers such as silicones.

A general polyurethane flexible foam formulation containing the catalystcomposition according to the invention would comprise the followingcomponents in parts by weight (pbw):

Flexible Foam Formulation

    ______________________________________                                        Flexible Foam Formulation                                                                   Parts by Weight                                                 ______________________________________                                        Polyol          20-80                                                         Polymer Polyol  80-20                                                         Silicone Surfactant                                                                             1-2.5                                                       Blowing Agent     2-4.5                                                       Crosslinker     0.5-2                                                         Catalyst        0.5-2                                                         Isocyanate Index                                                                               92-115                                                       ______________________________________                                    

The urethane catalyst composition consists essentially of the additionproduct, or adduct, of a tertiary amine urethane catalyst and a boroncompound of the general formula:

    R.sub.n B(OH).sub.3-n

where

n is 0 or 1, and

R is C₁ -C₈ alkyl, C₅ -C₈ cycloalkyl or C₆ -C₁₀ aryl.

Alkyl groups would include, for example, methyl, ethyl, butyl,ethylhexyl and the like; cycloalkyl would include, for example,cyclopentyl, cyclohexyl and the like; and aryl groups would include, forexample, phenyl, p-tolyl and the like.

Exemplary of suitable boron compounds are boric acid, phenylboronic acidand isopropylboronic acid. The preferred boron compound is boric acidwhere n is 0. Contemplated as functional equivalents to boric acid forpurposes of this invention are the borate esters, i.e., alkyl-, dialkyl-and trialkylborates, in which the alkoxy groups hydrolyze to thehydroxyl functionality in the presence of water.

It is also contemplated that any tertiary amine suitable as a urethanecatalyst can be used in making the amine-boron adduct catalystcomposition. Illustrative of suitable tertiary amine urethane catalystsare pentamethyldiethylenetriamine, pentamethyldipropylenetriamine,bis(dimethylaminoethyl) ether, dimethylcyclohexylamine,N,N,N'-trimethyl-N'-hydroxyethyl-ethylenediamine, triethylenediamine("TEDA") and the like.

Typical molar ratios of tertiary nitrogen to boron in making thecatalyst composition are from 1:0.01 to 1:100, preferably 1:0.1 to 1:10,most preferably 1:0.5 to 1:1.

Such catalyst compositions are generally easily handled solids which areprepared by precipitation from appropriate solvents upon mixing thetertiary amine with the boron compound at temperatures from ambient (orlower) to about 50° C., i.e. without substantial heating, and anyconvenient pressure, especially atmospheric pressure. In addition, solidadducts are afforded upon mixing the tertiary amine and the boric acidin a non-solvent for the adduct, again without the need for substantialheating. For example, TEDA and boric acid can be blended intetrahydrofuran or methoxyethoxyethanol to yield a solid product.

The amine-boron adducts are also easily prepared and more convenientlydelivered as solutions in carriers such as water, alcohols, polyols,amines, polyamines, ethers, hydrocarbons and chlorinated hydrocarbons.The preferred carriers are water, alcohols and polyols. The morepreferred carriers are standard polyurethane additives such as water,crosslinkers (e.g., diethanolamine), chain extenders (e.g., butanediol),and higher molecular weight polyether and polyester polyols. When usingphenylboronic acid, it is preferred first to dissolve the tertiary aminein the carrier and then add the phenylboronic acid.

A catalytically effective amount of the catalyst composition is used inthe polyurethane formulation. More specifically, suitable amounts of thecatalyst composition may range from about 0.01 to 10 parts per 100 partspolyol in the polyurethane formulation.

The catalyst compositions may be used in combination with other tertiaryamine and organotin urethane catalysts well known in the urethane art.

These catalyst compositions have the advantage of substantially reducedamine odor relative to standard tertiary amines while exhibitingcomparable or improved catalytic activity. The catalyst composition alsomanifests reduced viscosity and lower corrosivity.

The following automotive formulation master batches were used in theExamples:

    ______________________________________                                        Automotive Formulation Master Batch I                                         PLURACOL 816 (conventional polyether polyol)                                                              40                                                pphp                                                                          PLURACOL 1003 (styrene-acrylonitrile filled                                                               60                                                polymer polyol)             60                                                DC 5243 (silicone surfactant)                                                                             1.2                                               DEOA-LF (85 wt % diethanolamine in water)                                                                 1.75                                              Automotive Formulation Master Batch II                                        Multranol 9143 (conventional polyether polyol)                                                            50                                                pphp                                                                          Multranol 9151 (PHD filled polymer polyol)                                                                50                                                DC 5043 (silicone surfactant)                                                                             1.75                                              DEOA-LF                     2.0                                               ______________________________________                                    

EXAMPLE 1

A 1:2 molar mixture of BL22 catalyst (a 70:30 wt/wt mixture ofpentamethyldiethylenetriamine and pentamethyldipropylene- triamine) andboric acid was prepared according to the following procedure. BL22catalyst (25 g), boric acid (17 g), and water (42 g) were combined anddissolved at room temperature over 30 min. The resulting solution hadminimal, if any, amine odor.

EXAMPLE 2

A 1:3 molar mixture of BL22 catalyst and boric acid was preparedaccording to the following procedure. BL22 catalyst (25 g), boric acid(26 g), and water (51 g) were combined and dissolved at room temperatureover 30 min. The resulting solution had minimal, if any, amine odor.

EXAMPLE 3

A 1:2 molar mixture of triethylenediamine ("TEDA") and phenylboronicacid was prepared by combining TEDA (1.25 g), phenylboronic acid (2.75g), ethylene glycol (6.2 g) and diethylene glycol (9.8 g) and dissolvingwith mild heating (˜40° C.) over several minutes. The resulting solutionhad minimal, if any, amine odor.

EXAMPLE 4

A 1:2 molar mixture of TEDA and boric acid was prepared by combiningTEDA (118.5 g), boric acid (131.1 g) and water (250 g) and dissolving atroom temperature over 30 min.

The following Comparative Example 5 to Example 16 demonstrate that thesereduced odor amine-boron compositions exhibit equivalent or improvedreactivity when compared to standard tertiary amine catalysts for theproduction of flexible molded polyurethane foam. Foams prepared usingthe new catalyst compositions have physical properties which comparewell to those for foams prepared using industry standard catalysts.

COMPARATIVE EXAMPLE 5 AND EXAMPLE 6

PHD polyol based formulations were prepared from master batchformulation II in which the DEOA-LF level was 1.75 pphp, 2.8 pphp waterand (a) 0.50 pphp DABCO 33LV® catalyst with 0.12 pphp DABCO® BL-11catalyst as the Comparative Example 5 control catalyst or (b) 1.2 pphpof a 50 wt % aqueous solution of 1:2 TEDA and boric acid (TEDA:BA) ofthe Example 4 catalyst. Foams were prepared on an Elastogran PU-20machine by combining each of the above formulations with an 80:20mixture of 2,4- and 2,6-TDI at a 1.05 molar ratio of isocyanate toactive hydrogen functionality in a 140° F. (60° C.) mold for 4 min.Catalyst performance and physical properties are given in Table A.

                  TABLE A                                                         ______________________________________                                        Catalyst      DABCO 33LV/BL-11                                                                             TEDA:BA                                          ______________________________________                                        Initiation time.sup.a (sec)                                                                 5.83.sup.b     5.80.sup.c                                       Extrusion time (sec)                                                                        31.04.sup.b    30.91.sup.c                                      String Gel time (sec)                                                                       42.64.sup.b    39.85.sup.c                                      Extrusion weight (g)                                                                        41.sup.b       16.9.sup.c                                       Pad weight (g)                                                                              628.4.sup.b    606.6.sup.c                                      ILD-25%       34.8.sup.c     35.0.sup.c                                       ILD-65%       110.0.sup.c    105.8.sup.c                                      ILD-25% R     28.0.sup.c     28.3.sup.c                                       Density (lb/ft.sup.3)                                                                       2.07.sup.c     2.09.sup.c                                       Airflow (ft.sup.3 /min)                                                                     1.36.sup.c     1.50.sup.c                                       Tear (psi)    1.47.sup.c     1.53.sup.c                                       Tensile (psi) 16.95.sup.c    19.21.sup.c                                      Strain (%)    76.98.sup.c    90.71.sup.c                                      Ball Rebound (in)                                                                           45.00.sup.c    49.50.sup.c                                      Compression set 50%                                                                         7.96.sup.c     8.07.sup.c                                       ______________________________________                                         .sup.a cream time                                                             .sup.b average of three shot sizes  4.00, 3.85 and 3.60 sec                   .sup.c average for foams poured at minimum fill (3.60 sec shot)          

COMPARATIVE EXAMPLE 7

The control catalysts, 0.35 pphp DABCO 33LV catalyst (containing 33 wt %TEDA and 67 wt % dipropylene glycol) and 0.24 pphp BL22 catalyst, and2.9 pphp water (3.2 pphp total water) were added to automotiveformulation master batch I and mixed well for 30 sec immediately priorto adding 41.6 pphp of an 80:20 mixture of 2,4- and 2,6-TDI (1.05 molarratio of isocyanate to active hydrogen functionality). After mixing wellfor 4 sec, the foam was allowed to rise freely at room temperature. Fullfoam rise height was measured immediately and again after aging for 24h.

    ______________________________________                                        top of cup 1 (sec)                                                                              9.33                                                        top of cup 2 (sec)                                                                              26.13                                                       string gel (sec)  45.49                                                       full rise (sec)   60.38                                                       initial full rise (mm)                                                                          407.56                                                      final full rise (mm)                                                                            367.52                                                      ______________________________________                                    

EXAMPLE 8

An experimental catalyst, 0.81 pphp of a 50 wt % aqueous solution of 1:2BL22 catalyst and boric acid prepared according to Example 1 (equivalentto 0.24 pphp BL22 catalyst), 0.35 pphp DABCO 33LV catalyst, and 2.5 pphpwater (3.2 pphp total water) were added to master batch formulation Iand mixed well for 30 sec immediately prior to adding 41.6 pphp of an80:20 mixture of 2,4- and 2,6-TDI (1.05 molar ratio of isocyanate toactive hydrogen functionality). After mixing well for an additional 4sec, the foam was allowed to rise freely at room temperature. Full foamrise height was measured immediately and again after aging for 24 h.

    ______________________________________                                        top of cup 1 (sec)                                                                              9.90                                                        top of cup 2 (sec)                                                                              26.50                                                       string gel (sec)  47.14                                                       full rise (sec)   58.77                                                       initial full rise (mm)                                                                          409.22                                                      final full rise (mm)                                                                            347.25                                                      ______________________________________                                    

EXAMPLE 9

An experimental catalyst, 0.98 pphp of a 50 wt % aqueous solution of 1:3BL22 catalyst and boric acid prepared according to Example 2 (equivalentto 0.24 pphp BL22 catalyst), 0.35 pphp DABCO 33LV catalyst, and 2.4 pphpwater (3.2 pphp total water) were added to master batch formulation Iand mixed well for 30 sec immediately prior to adding 41.6 pphp of an80:20 mixture of 2,4- and 2,6-TDI (1.05 molar ratio of isocyanate toactive hydrogen functionality). After mixing well for 4 sec, the foamwas allowed to rise freely at room temperature. Full foam rise heightwas measured immediately and again after aging for 24 h.

    ______________________________________                                        top of cup 1 (sec)                                                                              10.73                                                       top of cup 2 (sec)                                                                              28.27                                                       string gel (sec)  46.92                                                       full rise (sec)   61.46                                                       initial full rise (mm)                                                                          409.68                                                      final full rise (mm)                                                                            348.19                                                      ______________________________________                                    

COMPARATIVE EXAMPLE 10

The control catalysts, 0.35 pphp DABCO 33LV catalyst and 0.24 pphp BL22catalyst, and 2.9 pphp water (3.2 pphp total water) were added to masterbatch formulation I and allowed to age for 15 h, then mixed well for 30sec immediately prior to adding 41.6 pphp of an 80:20 mixture of 2,4-and 2,6-TDI (1.05 molar ratio of isocyanate to active hydrogenfunctionality). After mixing well for an additional 4 sec, the foam wasallowed to rise freely at room temperature. Full foam rise height wasmeasured immediately and again after aging for 24 h.

    ______________________________________                                        top of cup 1 (sec)                                                                              9.68                                                        top of cup 2 (sec)                                                                              26.29                                                       string gel (sec)  44.79                                                       full rise (sec)   59.05                                                       initial full rise (mm)                                                                          409.14                                                      final full rise (mm)                                                                            367.54                                                      ______________________________________                                    

EXAMPLE 11

An experimental catalyst, 0.81 pphp of a 50 wt % aqueous solution of 1:2BL22 catalyst and boric acid prepared according to Example 1 (equivalentto 0.24 pphp BL22 catalyst), 0.35 pphp DABCO 33LV catalyst, and 2.5 pphpwater (3.2 pphp total water) were added to master batch formulation Iand allowed to age for 15 h, then mixed well for 30 sec immediatelyprior to adding 41.6 ppph of an 80:20 mixture of 2,4- and 2,6-TDI (1.05molar ratio of isocyanate to active hydrogen functionality). Aftermixing well for an additional 4 sec, the foam was allowed to rise freelyat room temperature. Full foam rise height was measured immediately andagain after aging for 24 h.

    ______________________________________                                        top of cup 1 (sec)                                                                              10.89                                                       top of cup 2 (sec)                                                                              28.00                                                       string gel (sec)  47.64                                                       full rise (sec)   59.94                                                       initial full rise (mm)                                                                          412.86                                                      final full rise (mm)                                                                            356.48                                                      ______________________________________                                    

EXAMPLE 12

An experimental catalyst, 0.98 pphp of a 50 wt % aqueous solution of 1:3BL22 catalyst and boric acid prepared according to Example 2 (equivalentto 0.24 pphp BL22 catalyst), 0.35 pphp DABCO 33LV catalyst, and 2.4 pphpwater (3.2 pphp total water) were added to master batch formulation Iand allowed to age for 15 h, then mixed well for 30 sec immediatelyprior to adding 41.6 pphp of an 80:20 mixture of 2,4- and 2,6-TDI (1.05molar ratio of isocyanate to active hydrogen functionality). Aftermixing well for 4 sec, the foam was allowed to rise freely at roomtemperature. Full foam rise height was measured immediately and againafter aging for 24 h.

    ______________________________________                                        top of cup 1 (sec)                                                                              11.93                                                       top of cup 2 (sec)                                                                              30.19                                                       string gel (sec)  52.20                                                       full rise (sec)   63.47                                                       initial full rise (mm)                                                                          411.90                                                      final full rise (mm)                                                                            356.37                                                      ______________________________________                                    

COMPARATIVE EXAMPLE 13

The control catalysts, 0.35 pphp DABCO 33LV catalyst and 0.24 pphp BL22catalyst, and 2.9 pphp water (3.2 pphp total water) were added to masterbatch formulation I and allowed to age for 15 h, then mixed well for 30sec immediately prior to adding 41.6 pphp of an 80:20 mixture of 2,4-and 2,6-TDI (1.05 molar ratio of isocyanate to active hydrogenfunctionality). After mixing well for 4 sec, the mixture was poured over11 sec into a five vent mold heated to 140° F. (60° C.), and allowed tocure for 4 min prior to demold.

    ______________________________________                                        extrusion (sec) 27.21                                                         string gel (sec)                                                                              36.26                                                         foam weight (g) 180.2                                                         ______________________________________                                    

EXAMPLE 14

An experimental catalyst, 0.81 pphp of a 50 wt % aqueous solution of 1:2BL22 catalyst and boric acid prepared according to Example 1 (equivalentto 0.24 pphp BL22 catalyst), 0.35 pphp DABCO 33LV catalyst, and 2.5 pphpwater (3.2 pphp total water) were added to master batch formulation Iand allowed to age for 15 h, then mixed well for 30 sec immediatelyprior to adding 41.6 pphp of an 80:20 mixture of 2,4- and 2,6-TDI (1.05molar ratio of isocyanate to active hydrogen functionality). Aftermixing well for 4 sec, the mixture was poured over 11 sec into a fivevent mold heated to 140° F. (60° C.), and allowed to cure for 4 minprior to demold.

    ______________________________________                                        extrusion (sec) 27.99                                                         string gel (sec)                                                                              38.83                                                         foam weight (g) 174.0                                                         ______________________________________                                    

COMPARATIVE EXAMPLE 15

The control catalysts, 0.35 pphp DABCO 33LV catalyst and 0.15 pphp DABCOBL-11 catalyst, and 2.9 pphp water (3.2 pphp total water) were added tomaster batch formulation II and mixed well for 30 sec prior to adding42.0 pphp of an 80:20 mixture of 2,4- and 2,6-TDI (1.05 molar ratio ofisocyanate to active hydrogen functionality). After mixing well for 4sec, the mixture was poured over 11 sec into a five vent mold heated to140° F. (60° C.), and allowed to cure for 4 min prior to demold.

    ______________________________________                                        extrusion (sec)   34.75                                                       string gel (sec)  44.17                                                       foam weight (g)   189.6                                                       residual weight (g)*                                                                            46.4                                                        extrusion weight (g)                                                                            28.0                                                        ______________________________________                                         *weight of foam remaining in the cup after pouring into the mold         

EXAMPLE 16

As experimental catalyst, 0.59 pphp of a 20 wt % solution of 1:2 TEDAand phenylboronic acid in a diethylene glycol/ethylene glycol mixtureprepared according to Example 3, 0.25 pphp DABCO 33LV catalyst, 0.15pphp DABCO BL-11 catalyst, and 2.0 pphp water (3.2 pphp total water)were added to master batch formulation II and mixed well for 30 secprior to adding 42.9 pphp of an 80:20 mixture of 2,4- and 2,6-TDI (1.05molar ratio of isocyanate to active hydrogen functionality). Aftermixing well for 4 sec, the mixture was poured over 11 sec into a fivevent mold heated to 140° F. (60° C.) and allowed to cure for 4 min priorto demold.

    ______________________________________                                        extrusion (sec)   39.63                                                       string gel (sec)  49.43                                                       foam weight (g)   188.4                                                       residual weight (g)*                                                                            45.2                                                        extrusion weight (g)                                                                            32.5                                                        ______________________________________                                         *weight of foam remaining in the cup after pouring into the mold         

Solutions of tertiary amines and the boron compounds R_(n) B(OR')_(3-n)can have much lower viscosity at comparable solids than previouslyreported amine-boron catalyst compositions. Low viscosity compositionsare conveniently handled, whereas highly viscous materials often need tobe heated to enable delivery into a commercial formulation.

COMPARATIVE EXAMPLE 17

The glycerol borate acid salt of TEDA was prepared according to U.S.Pat. No. 3,113,515. Boric acid was combined with 2 molar equivalents ofglycerol and hested to 180° F. to afford a glycerol borate acid. Thereaction mixture was then cooled to 100° F. and treated with 1 molarequivalent of TEDA. Further cooling afforded a viscous materialcontaining 30 wt % TEDA which had a measured Brookfield viscosity of14,800 centipoise at 25° C.

EXAMPLE 18

An aqueous 1:1 TEDA/boric acid molar mixture was prepared by dissolvingTEDA in water and adding 1 molar equivalent of boric acid under ambientconditions. Dissolution of the boric acid was rapid, resulting in amodest exotherm (<50° C.). The resulting solution which was 33 wt % TEDAand 50 wt % solids had a measured Brookfield viscosity of 16 centipoiseat 25° C.

Catalyst compositions of this invention have also been found to benon-corrosive according to a standard static NACE corrosivity test.Comparable strong acid blocked tertiary amine catalysts exhibitvariable, however, typically significant, corrosion of carbon steel.

EXAMPLE 19

A series of tertiary amine-boric acid compositions was evaluated forcorrosivity according to a standard static NACE corrosivity test.Coupons prepared from 1010 carbon steel were partially submerged in thecatalyst solution. Corrosion as measured for the liquid and vapor phasecontact as well as at the liquid/vapor interface. Comparative data wasobtained for several commercially available acid blocked tertiary aminecatalysts. The following Table B summarizes the results.

                  TABLE B                                                         ______________________________________                                        Catalyst Corrosivity                                                          Catalyst      Environment                                                                              Corrosion Rate                                       ______________________________________                                        TEDA/H.sub.3 BO.sub.3.sup.a                                                                 liquid     <0.10 mils/yr                                        TEDA/H.sub.3 BO.sub.3                                                                       liquid      0.11 mils/yr                                        TEDA/H.sub.3 BO.sub.3                                                                       liquid/vapor                                                                             --                                                   TEDA/H.sub.3 BO.sub.3                                                                       vapor      <0.10 mils/yr                                        TEDA/H.sub.3 BO.sub.3                                                                       vapor      <0.10 mils/yr                                        DABCO 8154.sup.b                                                                            liquid      12.2 mils/yr                                        DABCO 8154    liquid      10.9 mils/yr                                        DABCO 8154    liquid/vapor                                                                             --                                                   DABCO 8154    vapor      <0.10 mils/yr                                        DABCO 8154    vapor      <0.10 mils/yr                                        BL-22/H.sub.3 BO.sub.3c                                                                     liquid     <0.10 mils/yr                                        BL-22/H.sub.3 BO.sub.3                                                                      liquid                                                          BL-22/H.sub.3 BO.sub.3                                                                      liquid/vapor                                                                             --                                                   BL-22/H.sub.3 BO.sub.3                                                                      vapor      <0.10 mils/yr                                        BL-22/H.sub.3 BO.sub.3                                                                      vapor                                                           DABCO BL-17.sup.d                                                                           liquid        4 mils/yr                                         DABCO BL-17   liquid                                                          DABCO BL-17   liquid/vapor                                                                             significant                                                                   corrosion                                                                     visible etching at                                                            interface                                                                     (.sup.˜ 1/16-1/8 deep)                         DABCO BL-17   vapor      <0.10 mils/yr                                        DABCO BL-17   vapor                                                           ______________________________________                                         .sup.a Example 4 catalyst                                                     .sup.b Acid blocked catalyst                                                  .sup.c Example 1 catalyst                                                     .sup.d Acid blocked catalyst                                             

We have also found that these reduced odor tertiary amine-boron catalystcompositions provide physical property improvements. The glycerol borateacid/TEDA composition described in U.S. Pat. No. 3,113,515 affordedsignificant foam shrinkage in uncrushed molded foams. We have found thatTEDA/boric acid compositions in water do not cause such shrinkage infive vent, hand-mixed molded foams.

COMPARATIVE EXAMPLE 20

The control catalyst, 1.0 pphp DABCO 33LV catalyst and 2.8 pphp water(3.2 pphp total water) were added to master batch formulation II. Foamswere made over 8 days by combining this formulation with 43.09 pphp ofan 80:20 mixture of 2,4- and 2,6-TDI (1.05 molar ratio of isocyanate toactive hydrogen functionality), mixing well for 4 sec, pouring over 11sec into a five vent mold heated to 140° F. (60° C.), and allowing tocure for 4 min prior to demold. Foams were removed from the mold withoutcrushing and allowed to age at least 24 h before physical propertieswere measured. Foam shrinkage was evaluated by measuring the molded foamthickness at its minimum and comparing to the actual mold depth (114mm).

    ______________________________________                                        extrusion (sec)       32.1   (av)                                             string gel (sec)      39.6   (av)                                             foam weight (g)       197.0  (av)                                             foam thickness (mm)   107    (av)                                             foam shrinkage (%)    6      (av)                                             ______________________________________                                    

COMPARATIVE EXAMPLE 21

A comparative catalyst, 1.10 pphp of TEDA/glycerol borate acid preparedaccording to Comparative Example 17 (containing 30 wt % TEDA), and 2.8pphp water (3.2 pphp total water) were added to master batch formulationII. Foams were made over 8 days by combining this formulation with 43.79pphp of an 80:20 mixture of 2,4- and 2,6-TDI (1.05 molar ratio ofisocyanate to active hydrogen functionality), mixing well for 4 sec,pouring over 11 sec into a five vent mold heated to 140° F. (60° C.),and allowing to cure for 4 min prior to demold. Foams were removed fromthe mold without crushing and allowed to age at least 24 h beforephysical properties were measured. Foam shrinkage was evaluated bymeasuring the molded foam thickness at its minimum and comparing to theactual mold depth (114 mm).

    ______________________________________                                        extrusion (sec)       34.3   (av)                                             string gel (sec)      43.4   (av)                                             foam weight (g)       191.6  (av)                                             foam thickness (mm)   98     (av)                                             foam shrinkage (%)    14     (av)                                             ______________________________________                                    

EXAMPLE 22

An experimental catalyst, 1.00 pphp of a 50 wt % aqueous solution of 1:1TEDA/boric acid (containing 33 wt % TEDA) from Example 18, and 2.3 pphpwater (3.2 pphp total water) were added to master batch formulation II.Foams were made over 8 days by combining this formulation with 42.18pphp of an 80:20 mixture of 2,4- and 2,6-TDI (1.05 molar ratio ofisocyanate to active hydrogen functionality), mixing well for 4 sec,pouring over 11 sec into a five vent mold heated to 140° F. (60° C.),and allowing to cure for 4 min prior to demold. Foams were removed fromthe mold without crushing and allowed to age at least 24 h beforephysical properties were measured. Foam shrinkage was evaluated bymeasuring the molded foam thickness at its minimum and comparing to theactual mold depth (114 mm).

    ______________________________________                                        extrusion (sec)       31.6   (av)                                             string gel (sec)      39.4   (av)                                             foam weight (g)       192.3  (av)                                             foam thickness (mm)   111    (av)                                             foam shrinkage (%)    2.6    (av)                                             ______________________________________                                    

STATEMENT OF INDUSTRIAL APPLICATION

The present invention provides an amine catalyst composition for makingpolyurethane foam products which exhibits reduced odor, reducedviscosity and lower corrosivity.

We claim:
 1. In a method for preparing a polyurethane foam whichcomprises reacting an organic polyisocyanate and a polyol in thepresence of a blowing agent, a cell stabilizer and a catalyst, theimprovement which comprises employing as the catalyst a compositionconsisting essentially of the addition product of triethylenediamine anda boron compound having the formula

    R.sub.n B(OH).sub.3-n

where n=0 or 1, and R=C₁ -C₈ alkyl, C₅ -C₈ cycloalkyl or C₆ -C₁₀ aryl.2. The method of claim 1 in which the composition is employed incombination with a tertiary amine urethane catalyst or an organotinurethane catalyst, or both.
 3. The method of claim 1 in which the boroncompound is boric acid.
 4. The method of claim 2 in which the boroncompound is boric acid.
 5. The method of claim 3 in which the tertiarynitrogen to boron molar ratio of the catalyst composition is 1:0.5 to1:1.
 6. The method of claim 4 in which the tertiary nitrogen to boronmolar ratio of the catalyst composition is 1:0.5 to 1:1.